The invention relates generally to agricultural equipment and more particularly to improvements in self-propelled harvesting machines which include a prime mover, a cooler and a cooling fan.
The operation of a harvesting machine often results in the formation of considerable dust and particles in the surrounding air. At the same time, such a harvesting machine must suck in a large amount of air in order to adequately cool the engine, which these days may have a power of 400 kW or more. In the harvesting machines being considered here, one has to ensure that any rotating suction device and any additional baffle plate sweep the outer surface of the filter to release and remove all the dirt particles adhering to the surface of the filter. This will then prevent the pores of the filter from becoming so clogged with dirt particles over the time period for which the machine is used that insufficient cool air can flow through the openings in the filter. As used herein, the terms "dirt", "particles" or "dirt particles" are intended to be generic and cover, for example, dust, chaff, particles of dirt, and particles of crop. The surfaces of the filter may additionally be swept from the inside by a baffle plate or be covered thereby. Such a device is known from EP 0 079 399.
That said, there is not much point in causing the cleaning device for the filter to be operated if the cooling-air does not really need to be cleaned. This is the case for example when travelling along the highway. Under certain circumstances, it is also possible for the number of dirt particles formed during harvesting to be so greatly reduced that it is no longer necessary to continuously apply suction to the surface of the filter. Operation of the suction device would then expend unnecessary energy and the rotating elements would be subjected to unnecessary wear and tear.
It is also known for cleaning devices to be switched on for cleaning the air filters in dependence on the operation of a member in the harvesting machine. Such a switching operation may be unsatisfactory from two points of view: the cleaning device may be operated during harvesting even though this may be unnecessary due to the small amount of dust being created; when travelling along the highway, the cleaning device may be switched off even though the harvesting machine may, for example, while driving along or having just left the fields, have sucked in some of the dirt deposited thereon so that the air filter really should be cleaned. In the case of forage harvesters in particular, the air cleaning device is located just above the base of a so-called maintenance chamber. Dirt particles inevitably collect on this base when the harvester is working in the fields. These particles are then sucked into the cooling fan when travelling along the highway and embed themselves in the filter device thereby substantially reducing the through flow of air.
It is an object of the present invention to overcome one or more of the problems discussed above.
Starting from a self-propelled agricultural machine including an air cleaning device of the type described above, the object of the invention is to reduce the time for which the cleaning device is operated.
These, and other objects and advantages of the present invention, will become apparent as the same becomes better understood from the following detailed description when taken in conjunction with the accompanying drawings.